Bladeless pump

ABSTRACT

A bladeless pump is described which uses a rotating impeller which is substantially smooth. The rotating impeller pumps fluid in a direction perpendicular to its direction of rotation. The moving part of the pump includes a substantially smooth or bumped outer surface, which rotates within a substantially unmoving part. The unmoving part includes grooves which are canted in a specified direction. The innermost surfaces of the grooves form a diameter which is similar to the outermost surfaces of the substantially smooth impeller. When the impeller is spinning, fluid flow between the grooves is prevented. This causes fluid flow generally in the direction of the grooves.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of the U.S. Provisional ApplicationNo. 60/140,897, filed on Jun. 23, 1999.

FIELD OF INVENTION

The present application relates to a pump which is formed of rotatingparts, which can operate without blades.

BACKGROUND

Rotating pumps often use blades or propellers to press a fluid in adesired direction. These blades can subject the liquids to harsh impact.

For instance, if the pump is used to pump blood, then the blades canactually cut or otherwise damage certain blood cells, resulting inhemalysis injuring the blood. In other cases, the blades can causecavitation and produce undesired gas bubble turbulence in the fluid.

SUMMARY

The present application teaches a bladeless pump for fluid flow. Whilethe pump has many different applications, one application of the pump isfor use in pumping blood and other multiphase flows of body fluids.Other uses include thrust generation and propulsion.

One aspect of the application discloses a pump with a moving part thathas a substantially smooth outer surface.

Other aspects include that outer surface having a substantially constantouter diameter. The moving part can be a rotating shaft held captivewithin an outer cylinder. The inside surface of the outer cylinderincludes ridges thereon which are tilted a specified angle. The optimumangle is believed to be 45 degrees. However, any angle a, between(0<a>90 degrees) can produce a pumping effect.

A specified relatively small distance is maintained between the rotatingsubstantially smooth inner surface, and the inside of the outer shell.This small distance can preferably be an amount that preventssubstantial leakage of fluid between the ridges.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects will now be described in detail with respect tothe accompanying drawings, wherein:

FIGS. 1-3 show different views of the pump from different angles;

FIGS. 4A and 4B show flexible pumps; and

FIG. 5 shows a propulsion system.

DETAILED DESCRIPTION

FIGS. 1 through 3 show different views of the pump of this embodiment.The pump is formed of two coaxial cylinders, one rotating within theother. An outer cylindrical housing 100 includes an outer surface 102which can be of any desired size or shape. The inner surface 104 of theouter housing is formed with spirally-patterned grooves 106 thereon. Thecentral axis 110 of the outer housing 100 defines a direction of fluidpumping.

A fluid pumping element 120 is located coaxially with the central axis110. The fluid pumping element 120 has a substantially smooth outersurface 122. It preferably has no blades thereon. Blades, as that termis used herein, are sharp edged objects, such as the usual fan-shapedparts that are used in a pump.

In one embodiment, the fluid pumping element 120 is cylindrical and hasa substantially constant outer diameter over its entire active surface.That constant outer diameter can be constant within 1 to 5 percent. Thefluid pumping element can be a solid element, or can be a hollowelement, such as a tube.

The pumping is held rotatably at its two ends by a first shaft holder130 and a second shaft holder 140. The shaft can rotate within the firstand second shaft holders. An electric motor 150 can provide rotationalforce to the end.

The chamber surface, formed by inner surface of the outer shell includesa plurality of grooves thereon. The inner surface can have a diameter ofID, which can range rom sizes for operation to pump microfluidicsranging to a size for submarine propulsion. The grooves are ranted at aspecified angle. Each of the grooves extends inward from the innersurface by a depth proportional to (OD-ID). The grooves are canted inthe direction of desired rotation of the central shaft and in thedirection of desired pumping. The pumping element can be rotated in theopposite direction to pump the fluid in the opposite direction.

The inner element, here smooth inner cylinder 120 preferably has anouter diameter of ID-2g, where g is the gap between the inner cylinderand the inner surface. The cylinder can also have smooth nose and rampportions.

In operation, the central shaft is rotated in the specified direction ata specified rpm rate, e.g. between 5,000 and 20,000 rpm. A shearingforce is produced proportional to the angular velocity of the innercylinder diameter of the inner cylinder. The momentum is transferred tothe rest of the fluid. This causes a laminar or turbulent flow aroundthe shaft and along the shaft/groove axis. The viscose or turbulentshear flow eventually extends outward to the grooves.

The angular momentum of the fluid in the grooves has a vector componentalong its axis, forcing the fluid to move.

The grooves are preferably spaced by a maximum distance of one quarterthe shaft diameter. However, there is no minimum effective minimumdistance for the groove spacing. A typical groove pattern is usuallycanted by approximately 45 degrees relative to the direction of thecentral axis.

In operation, when the shaft spins, it causes a shearing laminar orturbulent flow around the shaft, thereby causing the fluid to flowoutward. The shaft is close enough to the grooves to cause fluid flow inthe grooves, and to prevent substantial leakage between the grooves.

The grooves facilitate the fluid flow movement. A particularlyadvantageous use of this pump is in blood flow. A known shear thinningeffect in blood causes the red cells to avoid the high shear regions.The cells distance themselves from the high speed-rotating shaft andleave the plasma near the rotating shaft. This process does not occurinstantaneously. However, in this pump, the approaching red blood cellsfeel the stagnation region of the smooth-surfaced rotating shaft. Theycells then start an avoidance process with enough lead-time on a viscosetime scale to avoid intersecting the path. Previous pumps that rely onthe displacement action of the blades at high angular frequencies andspeeds often do not leave enough response time for the red blood cellsto avoid impact, and its subsequent damaging effects.

The present application pumps the red blood cells without using blades.Hence, there are no blades to cut into blood cells. The shear thinningeffect causes the cells to stay away from the high shear portions. Thegrooves that are used can also be rounded to minimize any damage thatcould be caused to the blood cells by those grooves.

Many modifications are possible. As disclosed above, the device can bemade in a number of different sizes, and the internal ridges can have anumber of different sizes and shapes. The area between the internalridges can be either edged or smooth.

The central shaft is preferably a constant diameter cylindrical rod.However, the shaft can alternatively be a varied diameter cylindricalrod or any other element that is smooth and does not include sharp edgesthereon. For example, the cylindrical rod could be formed with an outersurface that has bumps that rounded edges.

The way that the pump works allows other advantages. No sharp cornerblades are used. Hence, the whole assembly can be made with flexiblematerials. One embodiment shown in FIG. 4 uses flexible tube 400 withinner grooves 405. A flexible cylindrical shaft or rod 410 rotateswithin the outer tube. This can be used for applications where localsuction or blowing in complex inner cavities would be required. Anotheralternative shown in FIG. 4B forms the inner rotating part 400 from aflexible material; so that it can be bent at the area 450 to attach thedriving motor.

A rotary motor 450 or any other kind of motor can carry out the rotationof any of these embodiments. One embodiment uses a magnetic levitationpump principle. According to this embodiment, the central shaft is madeof a magnetic material. An external coil will generates magnetic field,and the external magnetic field causes the internal cylinder to rotate.The rotating cylinder causes the fluid flow as described above.

One embodiment is for use in propulsion, e.g., as a motor to drive awater vehicle such as a submarine. This embodiment is shown in FIG. 5with two propulsion pumps 500, 510 with rotating elements 502, 512 thatrotate in opposite directions 504, 514. The cylinders have oppositelycanted ridges 506, 510 so that they both pump in the same direction.This allows balance in the thrust generation. A control element 520enables setting the rotating speed of each element individually. Thethrust vector, caused when one of these moves faster than the other, canbe used for maneuvering. For example, the left side pump part 500 can beinitiated to pump faster than the right side pump part 510 to move in amore rightward direction.

This system has advantages when used for propulsion, e.g. thrustgeneration. The resulting system can be relatively quiet, since noblades cut the water.

This system also has advantages when used for pumping other materialsthat should not be damaged, besides blood. For instance, since anembodiment can be used which has no moving edges, this system can beused for pumping live aquatic animals or other damageable materials.

Other modifications are contemplated.

What is claimed is:
 1. A pump, comprising: an inner element, which isrotatably mounted to rotate around a rotation axis, and which hassubstantially smooth outer surfaces which has a substantially constantand continuous other diameter cylindrical surface; and a chambersurface, surrounding said first element and having an inlet for inlet offluid, at a first location along said rotation axis and outlet foroutputting pumped fluid, at a different location along said rotationaxis.
 2. A pump as in claim 1, wherein said chamber surfaces includesinternal grooves thereon.
 3. A device as in claim 2, wherein saidgrooves are canted at a specified angle that is not 0 degrees or 90degrees relative to said rotation axis.
 4. A pump as in claim 1, whereineach of said first element and said chamber surface are flexible.
 5. Apump as in claim 2, wherein said inner element is sized relative to saidinternal grooves such that fluid flow between internal grooves isprevented when said inner element is rotating.
 6. A pump, comprising: aninner element, having bumps thereon which is rotatably mounted to rotatearound a rotation axis, and which has substantially smooth outersurfaces which has a substantially constant and a continuous otherdiameter cylindrical surface; and a chamber surface, surrounding saidfirst element and having an inlet for inlet of fluid, at a firstlocation along said rotation axis and outlet for outputting pumpedfluid, at a different location along said rotation axis.
 7. A bladelesspump, comprising: a rotating part, which has no blades or groovesthereon and which rotates to produce a fluid flow in a directionsubstantially perpendicular to a direction of rotation.
 8. A pump as inclaim 6, wherein said first rotating part is substantially cylindricaland of constant diameter.
 9. A pump as in claim 6, further comprising amotor part which rotates said first rotating part.
 10. A pump as inclaim 9, wherein said motor part is an in line rotating motor.
 11. Apump as in claim 9, wherein said motor part is a magnetic levitationmotor.
 12. A pump as in claim 7, wherein said rotating part includesbumps thereon.
 13. A pump as in claim 7, further comprising a chambersurface, surrounding said rotating part, and which includes an innersurface with ridges, a part of said ridges adjacent to an outer surfaceof said first rotating part.
 14. A pump as in claim 7, wherein saidrotating part is substantially smooth and cylindrical.
 15. A pump as inclaim 14, wherein said rotating is part of a substantially constantdiameter over an operative surface.
 16. A pump as in claim 14, whereinsaid rotating part has a diameter which is similar to a diameter of saidridges, and which is of a size that prevents fluid flow between saidridges when said moving part is moving.
 17. A pump as in claim 13,wherein said ridges are canted in a specified direction which is notzero degrees or 180 degrees relative to an axis of said rotating part.18. A method of pumping a fluid, comprising: rotating a substantiallysmooth rotating element which has no sharp edged parts thereon; andusing said substantially smooth element to pump the fluid in a directionthat is substantially perpendicular to a direction of said rotating. 19.A method as in claim 18, wherein said fluid is blood.
 20. A method as inclaim 18, wherein said fluid includes living organisms therein.
 21. Amethod as in claim 18, wherein said substantially smooth surfaceincludes bumps thereon.
 22. A method as in claim 18, wherein itssubstantially smooth surface is cylindrical and has a substantiallyconstant diameter.
 23. A method as in claim 18, wherein saidsubstantially smooth surface rotates within another surface which hasridges thereon.
 24. A method as in claim 23, further comprising rotatingsaid pump in a direction whereby the ridges are canted in a direction offluid flow by an amount that is not 0° or 90° relative to a direction ofsaid rotating elements.
 25. A method as in claim 23, further comprisingsizing said substantially smooth surface such that it prevents fluidflow between said ridges when rotating.
 26. A method as in claim 18,wherein said rotating part is flexible.
 27. A method of pumping blood,comprising: forming two coaxial cylindrical elements; rotating one ofsaid elements relative to the other, and introducing blood to saidelement to pump the blood in a direction perpendicular to a direction ofsaid rotating.
 28. A method as in claim 27 wherein said system operateswithout blades cutting the fluid flow.
 29. A method as in claim 27wherein one of the elements does not move, and the non-moving elementincludes ridges on a surface thereof.
 30. A method as in claim 29wherein the non-moving element has ridges that are canted at a 45°angle.
 31. A method as claim 30 wherein the grooves are spaced by adistance smaller than ⅓ a diameter of the rotating element.
 32. A methodas in claim 29, wherein said moving element has an outer surface sizewhich is substantially similar to an inner surface size of a highestpart of said ridges of said non-moving element, by an amount which iseffective to prevent fluid flow between said ridges.